Method of making a reinforced composite concrete pipe

ABSTRACT

METHODS OF MAKING REINFORCED CONCRETE PIPES WHICH ARE SUBSTANTIALLY IMPERVIOUS TO THE ENTRANCE OF ADVERSE CHEMICALS. THE PORES AT THE OUTSIDE OR INSIDE SURFACES OF THE CONCRETE PIPE ARE FILLED AND COVERED WITH A POLYMERIZABLE POLYMERIC RESIN COMPOSITION WITH GLASS FIBERS BEING EMBEDDED IN THE RESIN COMPOSITION.

Feb. 16, 1971 RUBEN5TE|N Re. 27,061

METHOD OF MAKING A REINFORCED COMPOSITE CONCRETE PIPE Original FiledDec. 11, 1957 4 Sheets-Sheet 1 INVENTOR.

Feb. 16, 1971 RUBENS-"5m Re. 27,061

METHOD OF MAKING A REINFORCED COMPOSITE CONCRETE PIPE Original FiledDec. 11, 1957 4 Sheets-Sheet :3

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F217. 16, 1971 RUBENSTElN Re. 27,061

METHOD OF MAKING A REINFORCED COMPOSITE CONCRETE PIPE 4 Sheets-Sheet 5Original F'iled Dec. 11, 1957 IN VENTOR.

Feb. 16, 1971 D, RUBENSTEN Re. 27,061

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IHVILIHUV United States Patent Int. Cl. B32]; 33/00 U.S. Cl. 156-456 34Claims Matter enclosed in heavy brackets appears in the original patentbut forms no part of this reissue specification; matter printed lnitalics indicates the additions made by reissue.

ABSTRACT OF THE DISCLOSURE Methods of making reinforced concrete pipeswhich are substantially impervious to the entrance of adverse chemicals.The pores at the outside or inside surfaces of the concrete pipe arefilled and covered with a polymerizable polymeric resin composition withglass fibers being embedded in the resin composition.

This is a division of application Ser. No. 702,050, filed Dec. 11, 1957,now U.S. Pat. No. 3,177,902, which application was a continuation-impartof copending applications, Ser. Nos. 668,285, filed June 25, 1957, nowabandoned, 345,084, filed Mar. 27, 1953, now abandoned, 229,852, filedJune 4, 1951, now U.S. Pat. No. 2,850,890, patented Sept. 9, 1958.

This invention relates to prestrcssed laminated pipe, tanks and vessels,and methods of making the same. An object of the invention is to provideprestressed reinforced concrete or other porous structural materialpipe, tanks or vessels highly resistant to dynamic loads while at thesame time sustaining designed-for loads.

An object is to provide interior and exterior surfaces materialcharacteristics adapted to substantially protect the fluids or othermaterials flowing through or stored in the concrete pipe, tank or,vessel or the like.

An object of the invention is to provide means for making plasticresin-fiber reinforced prestressed reinforced concrete pipes, tanks andvessels.

An object of the invention is to improve existing constructionscomprising pipes, tanks and/or vessels to make such constructions highlyresistant to residual nuclear radiation that might follow the explosionof an atomic bomb.

An object is to reinforce the interior and exterior surfaces andmaterials adjacent said surfaces made out Of porous structuralmaterials, e.g., concrete or clay prod- Re. 27,061 Reissued Feb. 16,1971 ucts, or other stone-like products and materials, so as to preventor minimize spalling" of the porous structural material.

A further object is to reduce the cost, improve the quality and improvethe engineering and structural functionality of pipes, tanks andvessels.

This invention provides materials possessing great strength in tension,laminated with materials of relatively low tensile strength butpossessing great compressive strength.

By virtue of this invention structural materials are provided suitablefor normal and extraordinary loading with compression loads, shearloads, tension loads, and/or torsion loads, whether or not subject totemperature changes, impact, shock or other distorting tendency.

The invention also makes it possible to design pipes, tanks and vesselswith properties and characteristics tailored to the particularrequirements of use. It is thus possible to accentuate any desirablecharacteristic, such as resilience, moisture and fluid resistance,shockproofing, light weight, thermal insulation, or thermalconductivity, smoothness, load bearing capacities in compression,tension, shear and torsion. All these capacities and properties can bedesigned into the resulting structure and all factory produced. Inaddition, by my invention, pipes, tanks and vessels are easily designedto be fireproof or fire resisting, and especially can be made chemicallyresistant to many adverse chemical influences.

These and other objects will be apparent from the drawings and thefollowing description thereof. Referring to the drawings, which are forillustrative purposes of embodiments of the invention;

FIGURE 1 is an isometric view of a circular concrete body having aplastic resin laminated interior construction of the invention;

FIGURE 2 is an isometric view f a circular concrete body having aplastic resin laminated exterior construction of the invention;

FIGURE 3 is a view of a spray-spinning machine and apparatus adapted forthe manufacture of embodiments of the invention;

FIGURE 4 is an end view of FIGURE 3;

FIGURE 5 is a sectional view of an embodiment of the invention andshowing apparatus adapted to making it;

FIGURE 6 is a view of a spray-spinning apparatus adapted to makeembodiments of the invention;

FIGURE 7 is a view of another means of making embodiments of theinvention;

FIGURE 8 is a view of an embodiment of the invention and prestressingapparatus for making it;

FIGURE 9 is a view of an embodiment of the invention, prestressingapparatus for making it and sprayspinning materials and apparatus;

FIGURE 10 is a cross section of a portion of the wall of a prestressedcylinder pipe, tank or vessel;

FIGURE 11 is a cross section of a portion of the wall of a prestressedreinforced laminated concrete pipe, tank or vessel embodying theinvention;

FIGURE 12 is a cross section of a portion of a looped reinforcement andwall of a portion of a prestressed laminated concrete pipe, tank orvessel;

FIGURE 13 is a cross section of a portion of the wall of a centrifugallyspun pipe having a laminated joint.

In my prior applications, I have disclosed and claimed high strengthstructural elements and the method of making them in which concretebodies or other porous structural material is provided with a hightensile strength surface layer integrally bonded in, on and to theconcrete or porous structural material, and, specifically I havedisclosed the use of plastic compositions and plastic resin compositionsreinforced with fiber glass or other high tensile fiber in woven orunwoven mat form, fabric, strands, slivers, cables, tapes, roving, etc.

The present invention provides circular closed or partially closedconstructions like pipe, tanks and vessels of porous structural materialhaving greatly improved strength features and surface constructionlayers resistant to impact, abrasion, erosion, chemicals, etc. Theseprestressed preloaded constructions employ prestressed preloads derivedfrom forces generated in and of chemical reactions used alone ortogether with mechanically and/ or thermally derived force systems.

Preformed porous structural materials, e.g., concrete of any desiredtype of mixture and strength provide compressionally strong material andis used as a set and cured and pre-shrunk component. Plastic resins,e.g., catalyst-activated, cross-linked polymers of synthetic resinscombined with modifying agents of inert fillers, extenders and/orpigments, elastomeric materials and rubbers of the type disclosed andclaimed herein provide the plastic resin reinforcement, binders andadhesive components. Such plastic resins may be polymerized as 100%solids in homogenous films as layers made in a single application,so-called one-pass application or can be made in multiple applicationseither placed at one time in sequence or at spaced apart times forconvenient processing. Fibers of fiber glass, the preferred fiber of thepresent invention, but not limited thereto, or natural fibers like hemp,cotton, sisal, etc., or synthetic fibers like nylon, polyethyleneterephthalate (Dacron), acrylic fibers (Orlon) or Dynel, etc., and/orfuzed quartz, aluminum-silicate (Fibrefrax), ceramic spun fibers, etc.,with fibers of both organic and inorganic fibrous materials being usedtogether in any combination, or used alone, to provide the non-metallicreinforcement and/or filler that I use as components of reinforcement.Prestressing type steel wire, cable or rod reinforcement is used aloneor in some constructions in combinations with plastic resin and/ orelastomeric compositions and with or without fibrous reinforcements.

It is known that concrete shrinks on curing. This shrinkage is variableand is generally considered to extend over a long time, with thegreatest amount of shrinkage occurring in about 28 days of curing undermoist curing conditions at normal temperatures, e.g., 72 F. It is knownhow to vary this time period of complex chemical reaction occurring inthe setting of concrete but substantially all concrete shrinks.

Concrete does not follow Hook's Law within the elastic limits of theconcrete, there being a certain amount of plastic flow under load.Identical deformation under load is followed by a slow secondarydeformation due to the applied load. In a concrete construction that isdeformed a fixed amount by applied load, the strain necessary tomaintain the deformation gradually decreases in amount to a lessersubstantially constant amount of strain resulting in a permanentinternal stress of the concrete.

In prestressing concrete by means of winding Wire or cables undertension about the concrete pipes, the wire is covered with concrete andcured about the wire. This results in adverse features of shrinkage ofcuring having to be taken into account and from said shrinkage allowancemade for the loss of prestressed preload in the wire.

I have found that a pre-shrunk" concrete, etc., i.e., a concrete orother porous structural material component substantially reducedshrinkage and plastic flow problems. Particularly, this is so in theimpregnated and permeated porous structural materials having theresinous compositions comprising substantial portions of its integratedcomposition. I have found that thinner shells or Walls can be usedbecause of the higher strength composite materials of concrete andresin. In this specification the word concrete includes by definitionany useful porous structural material made with portland cement or,e.g., made with resinous binders in place of portland cement. Also thecomposite materials provide a concrete, etc., structure adapted to usein places where concrete or similar porous structural materials fail,e.g., for various reasons, e.g., acid soil or salt water or ground watercorrosion borne materials. Pipe and vessels as used in chemicalprocessing are more easily made by my invention and are chemicallyresistant and less costly to make.

To overcome the inherent structural limitations that coating on asurface of a porous structural material causes by the failure of bond atthe adhesive interface by reason of impact or adverse loading. I make asurface construction layer having very substantially constructedanchorages into and of the porous structural material, which e.g., maybe a concrete material comprising the compression material component ofthe embodiment of the invention, with a resin, or resinous orelastomeric composition placed on and into the body of said porousstructural material, provides, when set in said body, a resin orelastomeric or resinous solid having a predetermined amount ofshrinkage. I have found that a provided balanced design is had in thesurface construction layer.

This shrinkage provides stressing means which utilizes the substantialand large forces resulting from the chemical reactions of e.g., thepolymerization of thermosetting resins and the like, as well as theexpansion forces of the materials of the laminate, whereby the plasticresins, resinous substances, resin-elastomeric substances andelastomeric substance and/or rubbers congeal, set, fix and shrink-fitinto place. The forces so generated at the same time prestress thematerials of the surface construction layer and its adjacent body ofporous structural material, e.g., concrete, which the plastic resins orresinous or elastomeric compositions inclose and bond together as wellas prestress the concrete bodies to which the laminations comprising thesurface construction layers are applied and on the completion of saidchemical reaction, e.g., polymerization, integrates the combination intoa unitary structure, e.g., a pipe section, a tank or a vessel.

This invention provides prestressing of preloads into concrete bodies bythe shrinkage forces provided by shrinking, condensing, tighteningaction which introduces said prestressed preloads into the porousstructural material, e.g., concrete, as the materials of the surfaceconstruction layer lamination undergo setting, cooling, solidification,chemical reaction, shrinking, condensing and unification with thepreformed, pre-shrunk porous structural body, e.g., concrete pipesection.

This can be likened to the same thing as occurs to a wooden Wheel when ablacksmith sweats-on a steel or iron rim and the wheel becomes tightenedas the wood of the wheel takes up the prestress stresses introduced bythe shrinking of the cooling iron or steel.

The transfer of stress into the precast concrete component isaccomplished by contact of the plastic resins, e.g., unsaturatedpolyester resins, or other resins that fill porous holes and intersticesconnected therewith and by the general porosity of the concrete, and onbonding to gether with the plastic resins, fiber glass, or other fibersor reinforcements, fillers, steel wire or cable reinforcements with theconcrete. The shrinkage stresses of the plastic resins, e.g.,unsaturated polyester resin compositions, and other components that comeabout by heating and cooling, setting or fixing and/or chemicalreactions thus introduce prestress forces into the concrete pipeconstructions and structural components thereof, preloaded for ultimateuse, and thus makes them stronger, resilient, flexible and better suitedto end uses.

The stressing means includes features and novel means which utilizes thesubstantial and large forces resulting from chemical reactions ofpolymerization of thermosetting resins and the like, and the expansionforces of the materials of the laminate, whereby the plastic resinscongeal. set, fix and shrink-fit into place. The forces so generated atthe same time prestress the materials of the laminate which the plasticresins inclose and bond together as well as prestress the concretebodies to which the laminations are applied and integrates thecombination into unitary structures and members as completed pipesections and lengths. The prestressing forces resulting from thechemical changes are measurable by the known shrinkage of the plasticresins or plastics used.

In combination with thermal pre-compression or tension forces, or forcesgenerated in-situ, the chemical forces provide means alone or incombination with thermal and mechanical prestressing to provideprestressed preload in and of and with the materials of the compositestructure making up the prestressed constructions, e.g., pipe, tank orvessel. The stresses of shrinkage resulting from such a reaction aschemically induced as, e.g., a polymerization reaction, said reactionchemically induced as, e.g., said reaction occurring in the setting of,e.g., an unsaturated polyester resin composition, are transmitted as thecomplex stresses of shrinkage in the plastic composition through theinterface bond area of the laminated structure or construction of pipe,tank or vessel as compressive stress in the surface of the bondedmaterials and the area adjacent the surface of the bonded materials.

FIGURES 1-13 illustrate various constructions of pipe, tanks or vesselswhich are coated, laminated and integrated on their surfaces and intheir body structures with plastic resin bonded fibrous reinforcements,e.g., fiber glass, which compositions may also contain other fillers,bonding agents, binders or reinforcements in addition to or instead ofthe fibrous materials, e.g., fiber glass fibers. Pipe, or tanks, orvessels as is shown in the figures are made and advantageously used forwater conduits, aqueducts, sewers, sewer manholes, sewage processingconstructions, fluid transmission lines in industry, commerce andmilitary operations, and irrigation systems. A typical embodimentcomprises a concrete body shown in section in FIGURES 1-13. Suchconstructions have an inner layer composed of fiber glass resincompositions (or other strong fiber or reinforcing strands) embedded andbonded by plastic resin compositions, advantageously polymeric resincompositions such as unsaturated polyester resin compositions, epoxyresin compositions or polyurethane resin compositions, or compatibleresinous compositions of two or more resins, elastomers or syntheticsubstances. The flowable characteristics, and in general, placementfeatures in the processing of such materials when made into formulatedcompositions of my invention together with end product features andcharacteristics of strength, durability, chemical resistance, loadbearing characteristics and features, etc., determine the specificformulated compositions I employ. The materials are worked and handledand processed for the best use of their structural and civil engineeringfeatures applied and used in the light of and knowledge of the art ofchemical engineering. The composite structure, e.g., a large conduit ofprestressed concrete is designed for specific end use and to meetspecific end conditions of use in the full and broad sense ofengineering design. The novel features of surface layer con.- structionand the strength and load bearing characteristics of such pipe aregreatly increased by the laminated con.- struction, the concrete beingexcellent for resisting compressive strains, the fiber glass plasticresin composition affording high resistance to tensile stresses andadding substantially to the compressive strength of the composite pipeas well as having high strengths in shear, torsion and compression inits use as a composite composed material.

Pipes thus made have improved K factor, C factor, or other designationdepending upon the flow formula used to express the coefficient ofsmoothness. In embodiments of my invention the surfaces are extremelysmooth and uniform, and as a consequence such pipe will deliver, e.g.,15 to 20% more water (or other fluid). Because friction loss is reducedto a minimum, turbulence and joint obstructions to flow are practicallyeliminated. This increase in efficiency permits economies by use ofsmaller pipe sizes. Resin bonded joints solve many problems, leakage andentrance of roots or other growths into pipes through joints beingrestricted or eliminated.

By way of a simple example, the strength of such an untreated rawconcrete pipe, e.g., as tested by an A.S.T.M. accredited testinglaboratory, showed crushing strength of 1350-1400 lbs. per lineal inchof pipe. When this same pipe had fiber glass-resin composition comprisedof 2 oz. fiberglass mat bonded, integrated and laminated in, on and tothe inside and outside surfaces of said concrete pipe with anunsaturated polyester resin composition which was cured and set to makethe construction a unitary product, the same tests with loading appliedon a standard three point bearing showed 500 lbs. per lineal inch ofpipe sustained before breaking, i.e., five times that of untreated pipe.Sufficient strength is thus developed to eliminate need for steelreinforcement. This test was stopped at the loading of 500 lbs. per inchand the sample remained intact, with the only evidence of impendingfailure a slight cracking of the concrete body barely discernible to theeye, and with no discernible failure in either the inner or the outerplastic resin composition fiber glass reinforced surface constructionlayers.

When such pipe is used in corrosive soils or for transmission ofcorrosive liquids, the plastic resin fiber glass construction protectsthe concrete and there is no danger of failure due to corrosion ofreinforcing rods, etc.

For various purposes where temperature or processing is desired, tubularor other shaped circulating lines can be contained Within the body ofthe side wall of a pipe construction. Thus, cooling liquids orprocessing fluids can be re-circulated in and around the pipe inside itsbody wall.

Some embodiments of the present invention can be driven as piling or aswell casing, and in such circumstances of use, its high strengthstranded reinforcing construction stands in good stead.

The plastic-resin-fiber-glass reinforced surface construction layersintegrated and bonded to the porous structural material, e.g., concretepipe body, can be made resilient and resistive, pliable and yet strongand able to take without failure greater strains and stresses, intension, compression, shear and torsion, e.g., as imposed by earth loadsor other designed loads, with a margin of safety for withstandingearthquakes, bombing and the like. In all cases concrete or other porousstructural material, protects plastic resin surface layer constructionsfrom heat and abrasion, and notch and scratch effects are avoided. Theplastic resin composition protects the concrete, or the like andstrengthens it.

If desired, a thin cylindrical steel core, or a plasticresin-fiber-glasslaminated core may be used within the pipe upon which wire, or fiberglass strands embedded in a plastic resin composition suitable forprestressing is Wound or spun on said core, Also this may be embedded ina suitable layer of concrete which is then cured and dried and theplastic resin composition, such as a polyester resin, e.g., anunsaturated polyester resin composition may be then applied by spraying,embedding, layering, painting, dipping or other method, includingsprayspinning, and into this layer of plastic resin and discrete bindingcomponents, fiber glass or other fiber, e.g., sisal,

hemp, cotton, nylon, rayon, polyethylene terephthalate (Dacron), acrylicfibers (Orlon), or other acrylic fibers of various kinds, syntheticfibers, etc., can be applied, and will bond and unite with the pipebody, this providing added strength as above described, and fluid-tightsealing of the surface obtained.

On a polished stainless steel core or mandrel, or aluminum core withhighly polished surface, or other mandrel covered with cellophane, orother kind of film or sheet, a coat of polyester resin (or otherselected resin) with or without filler, for example, and can bespray-spun by revolving the mandrel beside a handily mounted spray gunon a sliding or geared support so that the sprayer travels up and downthe length of the mandrel so that an even amount coat of resin plasticcomposition is deposited on the mandrel. On another sliding or gearedsupport fiber glass films, mats, cloths, unidirectional fibers, flock,multidirectional fibers, rods, cords, cables. roving, tapes etc.,advantageously of fiber glass, are carried and fed onto the mandrel asit is coated with the plastic composition so as to reinforce by itsincorporation into the body of the plastic resin composition. Thus afiber-resin layer is built up on the mandrel to a desired thickness forrequired strength and is securely made into a homogeneous crosssectionof the fiber-reinforced-plastic-resin composition.

By using a heated mandrel, the plastic-resin-composition can beimmediately cured at the desired speeds, or air-setting plastic resinsmay be used which cure up on the mandrel Without heat. On withdrawingthe mandrel, or on removing the product made, and on removing thecellophane or equivalent liner from the inside surface of the pipe, thepipe will be found to have an exceptionally smooth and almost perfectsurface, the coefiicient of smoothness being to better than existingpipes.

It is important to note that the fiber glass in this liner is fullyprotected by the plastic resin composition against leaching and abrasionfrom substances carried in the fluids which may pass through the pipe.To assure such protection, the fiber glass or in fact any other fiberused, before it is applied on the mandrel or as it is applied on themandrel, is thoroughly coated with the resin composition, e.g., by thespray gun or e.g., by being processed through an impregnating apparatus.For this purpose the second mandrel from which the fibrous material isspun or unrolled, is co-ordinated with the spray gun for the resin sothat the fibers are well coated and shielded as they come to rest on themandrel and are further coated by spraying the plastic resin compositionthereon until the desired thickness is reached and achieved. Theresulting reinforced plastic-resin-composition-fiber pipe or pipe linermay be finally united with the preformed and cured concrete or otherporous structural material pipe body. This may be facilitated byimpregnating and coating the concrete with a bonding-type resin or resincomposition such as an unsaturated polyester resin, ormodified-polyester resin as known in the art, the surfaces of 'which arethen prepared for the fiber-resin composition lamination by properlysanding or grinding, or by treatment with a chemical, e.g., acidwashing, which assures an integral bonding of the lamination to thesurface construction layer or coating that is bonded thereto.

In FIGURE 12 is shown another method of anchoring thefiber-resin-composition-surface-construction-layer to the porousstructural material, e.g., concrete. In this case the fiber glass orother fiber reinforced resin facing is extended in a series of loops,i.e., cable-like loops 77, in which the fiber is protected by shieldingwith the plastic resin composition, as hereinabove mentioned, and theseloops project into the concrete body to give anchorage for the facing.With this method of manufacture, the facing may be preformed with theseloops and the concrete applied as a coating, e.g., by the spray-gun"method or by casting in suitable forms. Also the concrete may be anon-cementitious type of sand alone or sand and aggregates having apolymeric resin binder in place of portland cement.

A series of sections of concrete pipe may be joined into a long pipeline or conduit of high strength by means of the fiber-resin facingformed in-situ, i.e., by spray-spinning, or other means, with effectsomewhat similar to that described in connection with the joining ofconcrete block or other structural elements of my invention disclosedand claimed in my copending applications. These constructions have hightensile strength plastic resin fiber reinforced surface constructionlayers and are unitary structures. Such constructions have highresistance to shock and therefore advantageous for use in areas whereearthquakes or bomb shock may be encountered, or wherever a rigidconstruction is required, but one which can accommodate substantialresilient flexure with no impairment to the units or the joints.

A further improvement can be accomplished by incorporating in theconcrete a quantity of polymerizable plastic material, eitherair-setting, or chemical setting, or thermosetting. When the concretemixture has been poured and set, the plastic-resin effects areinforcement of the concrete. Before the resin in the concrete is fullycured, it may be softened or melted by heating or chemically combined,i.e., the resin, and thereby improve bond with the concrete or with thefacing or reinforcing material at the surface of the concrete.

There are many types of resin fabrics which can be used with myinvention, among which particularly may be mentioned the polyesterresins, silicone resins, synthetic rubbers and natural rubbers, epoxyresins, polysulfide rubber resins, polyamine resins, polyurethaneresins, each of which may be used alone or in combination with otherplastic resins. Binders of many different qualities are available, andin the application of the present invention one may choose among othersalready available and those which may hereinafter be developed to meetparticular requirements of any application of the present invention.

It is to be understood, also, that the present invention is not limitedto the use of any particular concrete aggregates or to organic orinorganic aggregates alone. Fillers, including cotton, wool, sisal,hemp, nylon, paper, cotton seed hulls, straw, grasses, wood, bamboo,and/or many other materials known to the art can be used in the practiceof my invention.

Although in most cases considerations of cost and structural propertieswill lead to the use of portland cement concrete, a variety of featuresand characteristics are obtainable by varying the choice of aggregates,cements, plastic resin binders, fillers, fibers, metals, etc., and theconcrete can be made, if desired, without using portland cement by useof cements other than portland cement, and even by use of plastic-resinsas the binding and cementing material of the and for the aggregate.Laboratory tests show good structural characteristics for concrete madein this manner. Where time is of the essence and one cannot Wait forPortland cement concrete to set and cure to its required strength, theuse of plastic resin composition or elastomeric composition can be usedand in the matter of minutes e.g., 5 minutes to 10 minutes as theaggregate binder sets and cures in such times, strengths are obtainedequal to and generally greater than many Portland cement concretes attheir 28 day cure.

In some cases the concrete may be omitted entirely and, for example,expanded plastics or other lightweight materials may be sandwichedbetween the high tensile plastic facings according to the presentinvention, which afford surface strength and shock resisting qualities.

For tanks, vessels and the like, the use of fiber glass mats, cloths,cables, ropes, roving, etc., around and/or within the concrete body isadvantageously used for prestressing. This can be accomplishedeffectively, quickly and inexpensively because it is possible to spraythe plastic resin binders under appropriate pressure that will firmlyfix the fiber glass or other reinforcing materials and at the same timeinsulate and shield the fibers from the concrete or other porousstructural material so that the prestressing member can be kept freefrom the deleterious effects of direct incorporation in the concrete.

FIGURES 1-13 inclusive, show shapes and constructions which are onlyillustrative and almost any conceivable shape that is required inindustry, military or civilian use can be made according to thisinvention.

An increase in the coefiicients of smoothness with improvement in thecarrying capacity or reduction in friction losses in concrete pipe linesis justified even at an increase if any, in cost because the use factorof concrete pipe lines distributes such cost over many years in use. 100years is not too much to expect from a well engineered concrete pipeline structure.

The improvement in surface provided by this invention wherein concretepipe is evaluated for its coefficient of smoothness and then compared tothe products of this invention, by test shows the surface of anembodiment of this invention to have 25% greater flow. The smoothnesscoefiicient of e.g., stainless steel or cellophane is the criteria I usefor smoothness coefficient because my invented pipe line surfaces ortanks or vessels are cast, laminated and made against such surfaces. Forequivalent flow in this design of pipe I can use 25% less pipe just onthe improvement made on smoothness.

From the above disclosure and that hereinafter given, and particularlyfrom the features applicable to the present invention from my copendingapplications and patents of issue, it can be seen that substantialbenefits and improvements are made in the flow characteristics,strength, impact resistance and chemical and environmental resistancesto structures like pipes, tanks and vessels. Chemical prestressing ofthe porous structural material greatly enhances the strength and utilityof the structures. Fibrous reinforcement e.g., glass fiber strands orroving has been tested at ultimate strengths of 300,000 to 5,000,000p.s.i. in tension having a 3% to 3 /2% elongation with recovery beforefailure under ultimate load. Commercial fiber glass fibers in laminatesalready tested show strengths of 50,000 psi. to 100,000 p.s.i. inflexural loading.

Referring to FIGURES l-l3 showing embodiments of my invention;

FIGURE 1 illustrates a round conduit, pipe or hollow cylinder or columnand is laminated and covered on the inside surface thereof with aplastic resin composition which may or may not have a filler thereforand bonded fiber glass fiber and/or other fillers, binders orreinforcements designed to meet usual or special structural designrequirements. Such requirements may be e.g., pipe for Water conduits oraqueducts, irrigation lines, sewers, fluid transmission lines inindustry and commerce, military pipe uses, civilian or militaryresidental piping, etc.

In the drawing of FIGURE 1 is illustrated the concrete 1, the glassfiber 2 and/or other selected fiber or reinforcement, and the plasticresin composition 3, e.g., polyester resin composition, or e.g., epoxyresin composition, or even a compatible mixture of epoxy-polyester resincomposition, or other adaptable resinous compositions. The strength andload bearing characteristics of such a pipe come from the laminatedconstructions, the concrete being excellent in resistance to compressionstress and the plastic resin composition glass fiber reinforcement beingpreferred but not limited thereto for the tensile stress reinforcement.

FIGURE 2 shows an embodiment wherein the exterior surface of a concretepipe line is covered, laminated and reinforced with a plastic resinfibrous reinforcement with concrete or other porous structual material1, fiber glass fibers 2. and plastic resin composition 3 beingintegrated and combined into a unitary construction.

FIGURES 3, 4, and 5 show apparatus for providing laminated concrete pipeconstructions adapted to providing many different embodiments of theinvention.

In this invention concrete pipe 1 is provided as a cured and driedprecast concrete pipe element. In many resin systems, but not allsystems it is essential to remove the water from the pores of theconcrete to insure designed bonding permeation and penetration of resinsubstances and compositions into the body of the concrete or the like.Fiber glass fiber 2 is provided as roving 63 which is fed into a rovingcutter 11 and blown by air which I may heat or may not heat dependingupon the resin setting characteristics of the composition 1 use in anyparticular formulation.

The chopped fibers are cut to any desired length, e.g., about 2" lengthand are varied in length for specific designs. The chopped fibers areblown into the duct 28 and out through distributor head 25 from whichthe fiber glass fibers are deposited and applied on the plastic resincomposition 3 as same is applied on the concrete 1 from spray head 4. Asthe fibers lay on the resin composition they are covered and built upinto a mat of any desired thickness making a resin-fiber fabriclamination to and with the concrete. Pressure is provided by air todrive the spray head and fiber distributor head and can be ad.- justedto various resin-fiber mixtures. The resin composition is supplied fromsupply tank 38 by pump 29 not shown, but in the apparatus, through pipe26 to distributor spray head 4. The plastic resin composition 3 andfiber glass fibers 2 feeding apparatus is mounted on support shaft 23.

A concrete pipe element 1 is placed on conveyor 15 so it can be spun bydrive rolls 33 one of which (or both) are driven by belt 31 which isdriven by motor 32.

A bearing 23 supported on a bar 17 is adapted to being raised so pipeelement 1 can be placed between the spinning abutments 14 and 16 and islocked in place with member 34.

The concrete pipe element 1 is closed at its ends with temporaryclosures 35 which are made of wood or metal or other material and thepipe element caused to spin at a selected speed while at the same timethe fiber glass fibers 2 and the plastic resin composition 3 aresprayspun onto the inside surface of the pipe to a predeterminedthickness and into a unitary bonded surface construction layer.

At times I first spray a resin composition layer on the concrete and geta desired penetration and permeation before I laminate the fibers 2 intothe resin composition layer. The pipe element 1 is caused to move backand forth on the conveyor by means not shown, or manually, to provide aneven layer of laminated construction on the inside of the pipe element1.

At other times I use one of my prepared enveloped constructions havingelongated strands 7 of fibrous material, e.g., fiber glassunidirectional fiber located and spaced for a given designedconstruction. I lay this prepared laminated enveloped construction in asticky bonding layer of plastic resin composition 3 which I havepreviously placed.

Another embodiment is made by placing a mat of dry fibers on a layer ofsticky bonding resin composition and the pipe element 1 rotated at aslow speed until the resin composition comes through the mat and thesticky resin thus saturates the mat. This in certain embodiments, butnot all, may be allowed to partially set after which the speed isincreased and additional resin composition and/ or fibers are placed tocomplete the laminated construction. The centrifugal force generallydrives the fibers down into the resin composition because the specificgravity of the glass fiber is greater than the resin composition whenthe resin composition is used with little or no filler therefor. Byincreasing the filler content, or by making the resin compositionthixotropic, balanced design can be had so that the fiber layer, if itbe a layer, can be supported between two layers of resin composition. Inthis way I make spun surfaces that are very smooth, about like glass,since in the process it is possible to orient the constituents of thecomposition to provide plastic resin surfaces of high gloss andsmoothness.

When I want directional reinforcement 7 in the laminate I use elongatedstrands 7 in predetermined alignment and direction, e.g., longitudinallyof the pipe element 1 or e.g., helically wound at a specific angle ofplacement.

FIGURE 6 shows the placing of fibrous strands 7 on a e.g., stainlesssteel mandrel 87 having a highly polished surface. The plastic resincomposition 3 is spray spun from spray head 4 as the mandrel rotates.The fiber 7 may be tensile fibers tensioned by apparatus shown in FIGURE8 to a predetermined preload which I increase in specific designs by theshrinkage features of the plastic resin composition used in thatspecific design, e.g., an unsaturated polyester resin composition havinga silica filler therefor. Concrete pipe element 1 can be made over themandrel and comprises a noncerncntitious concrete made of silica andresin composition bonded by heat or chemical reaction and be the porousconcrete material of the pipe element 1. Also alternatively, theconcrete pipe element 1 can be slipped over a prepared laminatedconstruction layer which is a preferred manner in many uses but not alluses.

The exterior surface construction layer is placed by the same apparatusand thus a concrete pipe element 1 can be laminated inside and outsideof its body surface to provide many different features of construction.

When pipe lines are to be exposed to chemicals in the earth or in use,e.g., oil field uses, or when salt water or corrosive fluids arecarried, or under conditions found in chemical plants, etc., theexterior surface of pipe lines having e.g., a polyester-epoxy resincomposition provides protection to the pipe line and its contents. Manyother resins or resinous compounds, but not all, resins, rubbers,elastomers, or compatible combinations thereof are available in the art,and are becoming newly available almost daily in the rapidly developingtechnology of plastics for use in specific and designed constructions ofthis invention. No limitation is intended in the specific examplesdisclosed herein, the requirements being as disclosed. The tensile,compression, shear and torsion strengths of the plastic resins, etc.,determine each particular use together with features inherent as foundin the materials or as modified by me in my formulations govern thedesigned uses of the materials. A chemically engineered product is madeproviding a civil engineering solution to any specific structure made.

FIGURES 7 and 8 show another embodiment wherein a porous structuralelement 1 is precast having grooves. Longitudinal cables orreinforcements 777 comprised of a plurality of strands 7 having endenlargements 77 are spaced in the grooves and end anchored by theenlargements 77 thereof. The opposite ends are placed in a pulling head56 through a bearing head 54 against which hydraulic jack 55 supportedby jacking head 57 against which said jack 55 exerts force and pullscables 777 or other type reinforcements, e.g., steel bars orequivalents, into a desired tensioned prestress preload. The jackinghead 57 is spaced from the rotatable end block 60 by spacers 58.Elements 54, 55, 56, 57, 58, and 60 comprise the prestressing apparatuswhen bolted together with bolts 51. The apparatus is adaptable forlength and for placing any loading of prestressed preload desired withinthe range of the jack and the strength of the apparatus. Theprestressing apparatus rotates on bearings 81 in a bearing groove ofmember 80. The apparatus can be used horizontally or verticallydepending upon the handling devices at hand for handling the elements.

Roving 63 is mounted on several unwinding spindles and a predeterminednumber of strands 7 are pulled through a spacing device 82 afterimpregnation and being covered with plastic resin composition 3 in goingthrough dipping vat 83. Guide roll 85 and hold down roll 84 help keepthe fiber oriented.

After the cables 777 are tensioned to a desired preload I spin theelement, e.g., a pipe section 1, in its hydraulic jacking apparatus andwhile under prestressed preload and wrap a predetermined number ofhelically wound strands 7 around the pipe element 1 and cover thegrooves 89 and cables 777 with the resin composition carrying helicallywound reinforcements. The layer is built up to a designed thickness and,if desired, an additional layer of plastic resin composition and afiller therefor is spray spun by means of the apparatus of FIGURE 7. Theapparatus can be used for any convenient length, the prestressing cables777 being made the length of the pipe, tank or conduit element 1 plusany additional length needed for anchorage and tensioning.

FIGURE 9 shows a complete plant equipment set-up for sprays, spinningand tensioning and compressing equipment.

A concrete base 68 is connected to two end supporting walls 48 throughwhich hearing sleeves 49 hold bearings 69 in shafts 50 can spin. A jackbearing harness 53 is securely locked to shaft 50 by element 52.

A precast concrete pipe element 1 is placed against jacking bearingharness 53 and jack pressure harness 54 is placed against the oppositeend of the precast pipe element 1. Jack 55 in its bearing harness 56 hastie rods 51 in it so that the tie rods 51 can be pushed through the pipeelement 1 and locked in place against the outer face of jack bearingharness 53. By the tie rods 51 being placed the pipe element 1 issecured to the rest of the jack harness. Back-up harness element 57 isplaced against the hydraulic jack 55 and spacer blocks 58 placed againstelement 57. The jacking apparatus is thus securely bolted againstrotator bearing harness 60 by tightening bolts 51. Rotator bearingharness 60 has shaft 59 securely locked to its body and shaft 59 extendsthrough end Wall 48 through bearing end 69.

With the tie rods 51 hand tight bolted and connecting the severalelements together the apparatus is now ready to induce a prestressedpreload into the concrete material of pipe element 1) by force generatedmechanically by the hydraulic jack element 55. By actuating jack 55 apredetermined selected amount of prestress preload is thus induced,i.e., puts the concrete material in compression preload.

When longitudinal cables 777 are used and the design calls for saidcables to carry a mechanically induced prestressed preload, the cables777 are inserted through the anchorages of elements 53 and 56 and theenlargements 77 of the cables 777 used as bearings whereby when the jack55 is actuated to a predetermined selected tensile stress preload, thenthe desired prestressed preload is thus induced into the said cables 7 77.

With the pipe element 1 in a state of compression prestressed preloadand the cables 777 in a state of tension prestressed preload the nextstep can be accomplished.

Motor 66 is started and speed control set at a predetermined selectedspeed. Shaft is rotated at this speed and spins drive pulleys 61 set insupport bases 62. With the drive pulleys 61 turning elements 53 and 60the entire spinning apparatus and prestressing jack device spins at adesired speed.

Strands of fiber 7 from roving coils 63 are fed through sizing rolls 43and 44 and pulled through feed rolls 41 and 42 and secured to a desiredplace on the pipe elernent 1 just prior to starting the spinning motionof the pipe element 1.

Spray guns 39 and 40 used together or on occasion alone, are started andplastic resin composition 3 drawn from tanks 35 and 36. The spray guns39 and 40 are mounted on a moving device, not shown, on shaft 46 so theycan travel at a selected speed and cover the fiber strands 7 as they arebeing wound on the turning pipe element 1. By advancing the guns alongthe pipe element 1 an even layer of plastic resin composition 3 isplaced and an even amount of fiber reinforcement 7 is embedded 13 andcovered. A surface construction layer of desired cross-section andhaving a desired selected amount of penetration and permeation of itsplastic resin composition in, and on and bonded with the concrete pipeelement 1 is thus formed.

The longitudinal cables 777 can be layed in the surface layer but I findthat a grooved construction is preferred when cables have anysignificant diameter, e.g., above A", but not limited thereto. Thecables 777 can be fiber glass strands or of roving, or of nylon strands,polyethylene terephthalate, acrylic fibers (Dynel or Orlon), metal,steel cable, rod or wire, or in fact any suitable tensile reinforcement.Cables 777 can be used without being prestressed but generally muchsaving in cost is had by prestressing, especially in long lengths. Theprestressed preload induced into the concrete material as a compressionload is captured and held permanently by the plastic resin compositionwhen it converts from its fluid fiowable state to its solid state. Bybalanced engineered design of components little or no loss of prestressdue to plastic flow of the composite construction is bad andconstructions like concrete pipe elements usually worked in loadingswhere an extra tensile or flexural load could cause failure in e.g., theconcrete component can by this invention be worked under more or lessprestressed loading and always keeping the concrete in compression andhaving it not enter the tensile phase. The apparatus of FIGURE 9 can beof any desired size and no limitation is intended. Handling equipmentand processing means are the criteria for size of elements processed andmade.

The shrinkage forces of plastic resins e.g., unsaturated polyesterresins induce prestressed preload into the composite construction as theresins set, fix, shrink and polymerize from a fiowable materialcomposition to a solid.

From the above disclosure a preferred method of making certainconstructions is the method of making a prestressed reinforced hollowcylindrical construction adapted to support substantial interiorpressures and external loading comprising the steps of providing atleast one preformed cylindrical hollow body of porous structuralmaterial, placing said body under compressive load, said load beingapplied at its ends and longitudinally of said body, applying an initiallayer of polymerizable resin composition which penetrates the surface toa discrete depth and permeates the body of said porous cylindrical body,applying a plurality of unidirectional strands of glass fiber undertension spaced substantially equidistant from each other on said bodyand spanning the said body longitudinally, and while applying additionalresin composition, embedding said glass fibers in said resin composition, bonding and curing said resin composition and embedded glassfibers to a set plastic-resin-glass-fiber reinforced material and oncompletion of said curing, release said porous cylindrical body fromcompression making said prestressed reinforced hollow cylindrical bodyreadyfor-use.

Thus is such a product made. The method of making a prestressedintegrally laminated hollow cylindrical construction adapted to supportsubstantial interior pressures and external loading comprising the stepsof providing at least one preformed cylindrical hollow body of porousstructural material, placing said body under compressive load, said loadbeing applied at its ends and longitudinally of said body, applying ininitial layer of polymerizable plastic resin composition whichpenetrates the surface to a selected discrete depth and permeates thestructure of said porous cylindrical body adjacent thereto and in theneighborhood of the surface and leaves a surplus of resin composition onthe exterior of said body, winding a plurality of helically disposedlayers of glass fiber roving under tension over and in said surplus ofresin composition on said body and while applying additional resincomposition embedding said glass fiber roving in said resin composition,bonding and curing in, on and to said hollow cylindrical body said resincomposition and glass fiber roving disposed therein to a set plasticresin-fiber glass reinforced integrally laminated prestressed hollowconstruction.

The method includes the method of making a prestressed reinforcedintegrally laminated hollow cylindrical construction as shown above inwhich in addition on said embedded plurality of unidirectional strandsof glass fiber and while applying additional polymerizable resincomposition, embedding and winding a plurality of helically disposedlayers of fiber glass under tension over said surface of said pluralityof resin embedded unidirectional strands of glass fiber and bonding andcuring in, on and to said hollow cylindrical body the said resincomposition and glass fiber strands and rovings to a set plastic resinfiber glass reinforced prestressed integrally laminated hollowconstuction.

FIGURES 10-13 show embodiments of the invention adapted to high pressurepipe concrete conduits.

In FIGURE 10 concrete pipe element 1 is precast against a metal shell,e.g., steel cylinder 12 and has known end ring connections, e.g., a bellring placed over a spigot ring which has a rubber gasket as disclosed inF. P. Jenkins Patent No. 2,348,477 issued May 9, 1944, or like thatdisclosed in L. G. Wilhelm Patent No. 2,407,009

r issued May 10, 1949. The steel shell 12 is spirally wound withprestressing wire 14 in the known manner. Since the prestressed steelreinforcement in this example is near the surface it is usually coveredwith a layer of concrete. In areas of contaminating environment, e.g.,acid soil, the steel reinforcement can be destroyed by acid actionthrough the thin concrete shell covering. In area of earthquake or thelike, vibratory forces tend to spall or crack the concrete and open thesteel to attack and corrosion.

By means of this invention a spray-spun" or otherwise applied laminatedlayer 10 of fibrous reinforcement 2 and resin composition 3 and having aresin filler therefor, e.g., silica powder or other protective fillers,e.g., an epoxy resin based lead filled thermosetting compound thatprovides a homogeneous laminated surface construction layer adapted foruse as a radioactive shield or, other high density shielding compounds.

Such a compound can be a composition of about to lead by weight and havea density of from 5.5 to 6.7 grams per cc. By reason of the epoxy resincomponent the compound is stronger than pure lead and even withoutfibrous reinforcement has more structural rigidity than pure lead. Otherknown materials other than lead useful for such purposes can be used asfiller, there being no limitation intended.

Polyethylene resin and lead can be used in a composition of about 90% to95% lead by weight and 5% to 10% by weight of polyethylene (hydrocarbonpolyethylene) which has a specific gravity of about 6.5 to 7.0 grams percc. The polyethylene lead binder does not contain nitrogen or oxygeneand consists essentially of molecules of C H The polyethylene containinglead is melted at about 210 to 230 F. into a low viscosity fluid. At themelting point temperature and up to 300 F. the fluid is of such a naturethat fibrous reinforcement pulled through a dipping vat and wrappedaround a concrete pipe element or block as in FIGURE 10 can be laminatedinto a layer of discrete thickness when I do the operation in acontrolled environment. By keeping the epoxy-lead composion fiuid it iseasily worked.

Other resins and substances can be likewise used and the art of resinscontains materials adapted to the present invention.

The two examples provide a smooth finish and high chemical inertness toacids, alkalies and other corrosive influencies and provide materialsadapted for use as a shield for nuclear applications. The high contentof lead aids in shielding against beta and gamma rays. The hydrogencontent in the polyethylene aids in shielding against neutrons. Theformulations are infinitely variable even in the present state of theart.

Joint 18 can be a preformed element which is of a packaged ready-for-useconstruction (or it can be made in place). It can be poured-in-place andof material like that of 10. Joint is advantageously made of epoxyleador polyethylenelead composition and poured in the field on theinstallation of the pipe element. Shoulder 22 aids in holding joint 18in place. Groove 26 can be a shape and size to receive joinery element18 for a secure fit thereof. The inside of the pipe element 1 isadvantageously laminated with a surface construction layer comprisingplastic resin composition 3, fibrous embedded reinforcement 2, e.g.,Fibrafrax, an aluminum silicate fiber, fiber glass fiber or a hightemperature ceramic fiber, laminated and bonded to pipe element 1 byfingers of resin and anchorages of plastic resin composition 78 in thebody of the pipe element 1.

Such a construction is designed to provide protection for potable watersupply mains, and conduits or the like, against residual radiationfallout which can be brought into water supply systems through theconcrete walls of the conduit systems, i.e., of the present concept ofconstruction.

FIGURE 11 is another embodiment wherein all reinforcement isnon-metallic being provided by glass fiber or other strands and fibers.A concrete element 1 is precast with longitudinal holes or slots inwhich to place cables 7. A helically spun fibrous reinforcement 28 isspun around the cables 7 and pipe element 1 and additional concrete 1 orresin-crete or elastomer-crete" of my invention is cast around the outerface. When this is cured and set a surface layer construction laminationof plastic resin composition 3, fibrous reinforcement 2 and/or 7, and asurplus of resin composition over that needed to impregnate the fibersis bonded into, on and of the concrete body of l as shown permeated intothe body at 78.

On the inside face of pipe element 1 laminated layers 32 and 34 areprovided bonded to a porous structural material 1 which has an innerlining surface construction layer of plastic resin composition 3,fibrous reinforcement 2 bonded to the said porous structural material11, e.g., lightweight concrete or e.g., high density concrete by fingersof resin composition 78. The cables 7 are secured by high strength resincomposition at the end anchorages. Ioints and joinery l8 and 20 can belaminated preformed joinery of my invention or can be poured in placeresinous or plastic compounds adapted to specific needs and uses. Abalanced designed construction is made from the various elements and thepreferred construction is adapted to resistance to high dynamic loads aswell as resistance to chemicals or radiative agencies. The resiliency ofstructure is of primary importance and I prefer embodiments being toughand rubbery and resilient rather than britle and hard. The original highcompression values of the concrete or other porous structural materialare increased substantially and the concrete properties in tension,shear and torsion are materially improved, and in a designed structuralengineering manner.

FIGURE 12 shows a preformed laminated construction layer having fibrouslooped cables reinforecement 7 a part thereof and extending in loopedfashion into the porous structure of the lamination. In this embodimentthe preformed laminated construction is provided packagedready-for-use-bonding and a concrete body cast around it and curedbefore the next step. A steel shell 12 may be used and an outer concreteshell may be used, or any of the features of FIGURES 21 and 22 may becombined in any specific construction.

FIGURE 13 shows a typical centrifugally cast concrete pressure pipeembodying features of the invention. Reinforcement 777 and 28 is firstassembled into a cage and then the concrete is spun around it as in theHume Process and cured. I have found that for certain concrete mixes aperiod of 3 to 7 days under moist curing is what is required followed by21 days of air curing. The knowledge of the art is relied on as concretemixes vary, environment varies and no general rule is acceptable.A.S.T.M. Labortaory approved tests are the only safe criteria safe touse. Other cemented mixes other than Portland cement can be used, evenplastic resin, and these are cured and made ready for laminating byfollowing the knowledge of the art of compounding as is known or as isdisclosed in my invention. Whatever aggregates are bound in a concrete,or a concrete-like-porous-structuralmaterial, are cured and made readyin accordance with an engineered structural engineering materials designof desired strength and use properties.

When cured, the concrete pipe element 1 is laminated by the methodsherein disclosed, i.e., on its inner and outer faces with a surfaceconstruction layer, e.g., an advantageously used layer of polyesterresin composition, or e.g., polyester-epoxy resin composition, or e.g.,an unsaturated polyester containing monomeric methyl methacrylateblended with 10% to 25% monomeric styrene or vinyl toluene and a fillertherefor and combined with fibrous strands, e.g., glass fiber roving.Reinforcement elements 777 are shown as glass fiber strands but anytensile reinforcement of metal or fiber alone or used together andadapted to any specific structural or civil engineering design may beused. Helically wound reinforcement 28 is advantageously glass fiber andplastic resin composition. The reinforcement 777 and 28 may be anembodiment of my invention comprising the packaged cable-likeconstructions packed ready for use as disclosed in my application Ser.No. 267,166, filed Dec. 17, 1951, and a portion of which is now PatentNo. 2,671,158.

The features of FIGURES 10-13 are combined in practice in embodimentsother than those shown and no limitation is intended in making anycompatible combination of construction.

Essentially, high pressure conduits designed to meet the environmentalconditions of earthquake, fiood, tornado and atomic blast is the productintended in the present invention. The accepted present criteria fordesign of such structures prior to this disclosure do not meet theindicated needs of atomic blast and never have adequately met those ofnatural natures forces like occurring in tornado or flood. The brittlecharacteristics of concrete or other porous structural useful materialsof high compressive strength and low tensile strength as is concrete, isdefinitely modified and improved in substantial amounts of strengths bythis invention. I make concrete take on new properties in flexure,tension, compression, shear and torsion, and particularly in fiexure bythe improvements of this invention wherein I chemically prestressprestressed preloads into concrete, by said chemical means alone, or incombination with thermal and/or mechanically induced prestressedpreloads. By changing the structural material characteristics of theconcrete or other porous structural material after it is precast andcured and pre-shrunk the very nature of concrete as a material ischanged by this invention. It is a composite material having theproperties of its original components and as set in combination with setplastic resin compositions that are reinforced with fibrousreinforcement, or are used alone for their own properties, or areplastic resin compositions containing selected discrete fibers. Concreteis a brittle glass like material which spalls on impacts. By thisinvention concrete is now a tough, rubbery, denser stronger material inwhich the concrete body provides in its pores the storage space for theplastic resin reinforcements in and of the body as well as the bestanchorages for laminations of glass fiber or other fibrousreinforcement, and as well as conventional steel and prestressing steelreinforcement in its body or on its body or in the laminated layer abovethe surface of the body of the concrete by being adhered and bonded tothe said porous structural body.

Join and joinery 75 is shown as a plastic resin fiber glass fiberreinforced laminated bonded bonding layer connecting and bonding twopipe elements together. The recessed surface of the exterior of the pipeelement near and at the joint and the configurations of surface at thispoint provide anchorages for laminated multiple reinforcement which isprovided advantageously in an enveloped packaged ready-for-usepolymerizable constructions and in use, is wrapped around the jointbetween the pipe elements. At will when the pipe is placed in a trench,e.g., and is aligned, the polymerization reaction is activated by meansof my invention and the joint construction is cured and set and securelybonded to make a fluid tight joint and at the same time act as astructural reinforcement in and of the joint. Combined with the pipeelement surface inside and outside laminated surface construction layersthe joinery thus employed working in a balanced designed constructionmakes greatly increased strength available and much better and moreuseful working surfaces of the composite construction.

In existing pipe lines the above described joinery can be advantageouslyused to make repairs.

The following examples show some but by no means all of the formulationsand constructions illustrative of the present invention:

EXAMPLE I A 36 diameter syphon in a water supply system is made asfollows:

Hume type centrifugal concrete pressure pipe is provided precast inlengths of 8 ft. to 12 ft. and having a 3%" minimum wall thickness andin its raw concrete state designed for to 150 ft. heads with maximumallowable unit stress in the steel of 12,500 pounds. The exteriorsurface of this pipe is to be protected against adverse chemical actionand I designated a A" thick plastic resin-fiber glass laminatedconstruction for this purpose as follows.

Mix design: Parts by wt.

Paraplex P-444 (Rohm & Haas Co.) an unsaturated polyester containingmonomeric methyl methacrylate and monomeric styrene or vinyltoluene-blended 80% Paraplex P-444 with 20% styrene monomer (or vinyltoluene) 100 Benzoyl peroxide 1 Aluminum silicate powder-ASP 600 25(This formulation will have a pot life of about 2.5 days at 77 F. andwill cure at 180 F. to 250 F. in about 2.0 minutes to 2.5 minutes)environment considered.

Color may be added if desired.

The concrete pipe sections are secured in the apparatus as shown inFIGURE 9 and rotated at a speed adapted to lay the glass fiber roving onthe concrete pipe body in an even layer, each roving being side by side.A sufiicient amount of resin composition is layed on the pipe body bythe spray guns to completely cover the pipe surface and provide enoughfor impregnation to a depth of 1" into the pipe body. The pipe isrotated until the A" crosssection is built up, it being subjected to ahot stream of air from time to time to set up the laminate and give afinal cure at a temperature of about from 180 F. to 250 F. Alternatecuring heat may be provided by infra-red lamps or by ambient curingmeans known in the art.

EXAMPLE II In making predetermined amounts of prestressed preload thatis induced into any given construction by the forces derived from thepolymerization reaction I have found that combination of resins eachhaving specific properties provides a sure and ready means of derivingspecific amounts of internal stress. An example stressing type ofplastic resin composition can be made by using polyesters based on avariety of polybasic acids and polyhydroxyl alcohols that contain freecarboxyl groups and/ or aliphatic hydroxyls capable of reacting with theepoxy resins. The wide range or molecular structures possible for thepolyester resins together with co-curing reactions occurring when theyare combined with epoxy resins provide me with resinous compositionsmodified to specific end uses. Polyesters of certain specificcharacteristics as well as polysulfides such as Thiokol rubbers are usedas flexibilizers. The effect of the polyester on the epoxy resin on thecombined properties is dependent on the acids and alcohols used in thesynthesis and on the number of members in the resulting resin chain. Ifother reactive elements are added, the properties can be varied evenmore.

The shrinkage of epoxy resins is of a low order while that of e.g.,polyester resins is of a relatively high order. Together with fillersand pigment I use the art and the knowledge of the art of resincompounding to provide specific stress characteristics.

Because of the toughness and high adhesive properties of the epoxiesthey provide upgrading agents for other resins like the phenolics,ureas, furanes, polyesters, melamines, vinyls, and fiuoro-carbons andeven asphaltic material or coal-tars. Thus the phenolic-epoxy resincompositions may be used to improve heat-distortion temperatures ofspecific resinous composition systems. Such lower priced synthetic resinsystems I find can be used in fairly high percentages to reduce overallcost of any specific-epoxy-resin system. Various phenolic resins andintermediates known in the art react with epoxy resins and cure them inthe presence of an acid or base catalyst, e.g., phosphoric acid, causticor dicyandiamide.

Urea formaldehyde and melamine-formaldehyde resin cross-link with epoxyresins through methylol groups. Furfural resins containing methylolgroups also act as modifiers for epoxy resin similar to methylol-bearingphenol and melamine resins to improve flexibility when used in the orderof 25 phr., to improve chemical resistance to acids, specifically tohydrofluoric acid when used on the order of 6S phr. and also furfuralresins reduce cost.

Vinyl chloride resins act as a heat stabilizer when combined with epoxyresin systems, the vinyl chloride resins losing HCl in the presence ofheat. Small percentages of vinyl chloride acetate with vinyl formalresins improve peel and impact strengths.

Isocyanates as polyurethanes react with hydroxyl groups present in epoxyresins claims to provide cross-linking. The isocyanate groups will reactwith primary and secondary amines and are capable of co-curing not onlywith the epoxies but with any amine curing agent present to providetightly cross linked structures. Monomeric diisocyanates such astolylene diisocyanate, diphenylmethane 4,4'-diisocyanate, and3,3'-butolylene 4,4'-diisocyanate are commercially available as reactivecross-linking intermediates.

Fluorinated resins while being insoluble in liquid epoxy resins and donot react with them can be combined in solution compounds to makeco-acting polymerizable resinous compounds which are excellent highadhesive materials having a low water transmission due to thefluorinated resins.

Silicone polymers are usually very weak and soft mechanically, but dohave high thermal stability imparted by the presence of the siliconatom. When combined with epoxy resin good mechanical properties andelectrical properties are provided in the combination. Modifications ofsilicone adhesives with 10 to 40% of epoxy resins having a degree ofpolymerization of 1 have resulted in a marked increase in shear strengthat 500 F Each particular resin formulation will exhibit its own specificproperties, and through the judicious selection of components, it ispossible to descign systems exactly suited to highly specialized enduses.

TYPICAL COMMERCIAL EPOXY RESINS Viscosity at Color Average 25 C. centi-Melting 25 C. E oxide molecular pulses or point Resin typo (Gardner) equvalent weight Gardner-Holt (Durans) Bakelite Col:

1 10 155-200 350-400 10, 500-19, 500 Liquid 1 170-182 350-400 11200191200 Liquid 1 9 194-470 340-400 500-900 Liquid E RLA-i-DOIepoxy/phenol! 1, 600-1, 700 1 25 Gina Co. Araldite 502 4 3, 000 Liquid.lones-Dabney Co. Biddle-e510 6 180-200 350-400 0, 000-12, 000 LiquidShell Chemical Co. pon Resins:

602 1 5 140-165 300 150-200 Liquid 820." 1 8 175-210 350-400 4, 000-10,000 Liquid 828 1 12 175-210 350-400 5, 000-15, 000 Liquid 815. 1 8175-210 340-400 500-900 Liquid 834. 1 10 225-200 450 Az-A Liquid 5 4, 18 300-375 700 Ay-B 40-50 1001 1 8 450-525 900-1, 000 C-(} 64-70 1004 1 6870-1, 025 l, 400 Q-U 95-105 1007 1 8 1, 650-2, 050 2, 000 I-Z 125-1321000 1 11 2, 400-4, 000 3, 800 Zg-Z5 145-155 1 Maximum. 2 Deg. 0.

a glycerol-based epoxy 100 Allyl glycidyl ether 10 Filler 100Triethylamine 12.5

A test formulation as follows was used with various fillers:

Parts by wt. Mixed polymer/epoxy resin 125 Trimethyl aminomethyl phenol10 EFFECT OF FILLERSON SHEAR STRENGTH OF ADHESIVE FORMULATION shearstrength, p.s.i.

Phenolic linen laminates tested at- Fillers, at 100 phr. 23 C 75 C. 900. 105 C.

Aluminum powder 2, 700 1, 410 1, 390 l nited A1203 4, 600 1, 360 1, 195530 Short-fiber asbestos 1, 740 1, 270 580 510 Carbon b1ack 2,000 555980 910 Silica 2, 840 1, 600 l, 250 830 Zinc dust 2, 51 600" 300 225 Thedata on epoxy resins is taken from Epoxy Resins by Henry Lee and KrisNeville, published from McGraw- Hill Book Company and from my own notesand development data.

EXAMPLE III In this example I make a prestressed reinforced integrallylaminated hollow cylindrical construction adapted to support substantialinterior pressures and external loading and having a smooth interiorsurface.

One formulation I use is made as follows:

Parts mix by wt. Polyester resin-Atlac 382 (dry resin) parts by wt 60Styrene monomer (fluid) parts by wt 40 Catalyst-Methylethyl ketoneperoxide in dimethyl phthalate 2 Aluminum Silicate (ASP-400) 30 Glassfiber roving 25 On a polished stainless steel mandrel having an internalheating device controllable to 5 F. plus or minus I spray spin a layerof the above resin composition to completely cover the mandrel as it isslowly spun. The resin composition is gelled as applied and into thisresin layer the fiber glass rovings are spirally wound as additionalresin composition is sprayed onto the mandrel until a predeterminedselected quantity providing the above crosssection is applied.

During the time that I am applying the above formulation onto themandrel, I also have a section of concrete pipe being dried of moistureand heated to about P. On the dried surfacel spray a layer of the aboveformulation of resin composition to which I add about 5% styrene monomerto get a desired penetration and spray until a desired amount of resincomposition gels on the surface of' the concrete. At this stage withboth the concrete surface'resin composition and the laminated fiberglass resin composition on the steel mandrel in a like gelled condition,I then slide the mandrel into the concrete pipe.

The heating device in the mandrel is advanced to 250 F. in this case andthe entire construction bonded together as the polyester resincomposition polymerizes to a cured state. The polyester resincomposition in the concrete and on it having additional styrene monomer(about 5%) shrinks more than 'the layer on the mandrel so that thelaminated layer is drawn in toward the concrete as the compositelaminated construction cures to a unitary construction.ori'coniplctionofthc cure' of the resin composition, inthis case about 4minutes, I cool the mandrel until the completed unit easily slidesofffrom the mandrel. The resulting interior surface construction layer isvery smooth and glass-like in its shiny appearance.

Variousother fibrous reinforcements can be used of which the'followingare illustrative but not limiting:

Ferro Unifab" style P970-Fiber glass cloth, finish 172 at 9.70 ouncesper sq. yd.;

Ferro Unirove style 545-Fiber glass woven roving;

Ferro UniformatHSB-2Fiber glass mat.

These reinforcements are in mat or fabric form and can be wrapped aroundthe mandrel in one or more plies and are sprayed with enough resincomposition to saturate the layer and with a surplus so roving whenWound around the layer or in between the layers of a plurality of layersare used to insure complete impregnation and coverage of the fibrousconstructions. Preimpregnated mat or hat or fabric can be likewise used.Glass fiber can be layed in place without being tensioned.

While a simple resin composition is given herewith, I use many differentcompositions known in the art and of my own invention and the generalmethod here given is used with such variations as the resin compositionsrequire in accordance with a design. By using a catalyst type gun likethe Binks gun or the De Vilbiss gun I spray spin a resmous compositionin two components so that a quick setting catalyst system can be usedthus speeding up the operation or for getting directly specificproperties to the total construction. Any adaptable resin compositionknown in the art thus can be spray spun into a resinous fabric orcomposition.

Alternatively, in place of spray spinning the glass fiber reinforcementsmay be pre-impregnated with a resin composition as known in the art andprovided ready for use or the glass fibers may be run through animpregnating vat before placement on the concrete or on a prior layedlayer of fiber reinforcement.

The following is a partial list of commercial materials I use:

Plaskon polyester resin 941-a rigid unsaturated polyester resin.

Plaskon polyester resin 9600'a flexible unsaturated polyester resin.

Plaskon polyester resin PE-l3(Self-extinguishing) chlorinatedunsaturated polyester resin.

Epon resin-Formulation XA200Solution A:

Percent by wt. Epon 100lfor solids content below 60% by Wt., thin withn-butanol-toluene,1,l.

Solution B is added to solution A with thorough stirring just prior touse and it also can be applied through a catalyst type two headed spraygun. The ratio of solution B to solution A will depend on the solidscontent of Solution A, but addition should be adjusted so that 6 parts(w) of pure ethylene diamine are added to 100 parts (w) of resin solids.Improved formulations are constantly being presented and no limitationis intended in the examples given.

An unsaturated polyester resin composition is as follows:

Polyester resin-Vibrin 117, parts by wt. 100 Lupersol DDMMethylethylketone peroxide in dimethyl phthalate, parts by wt. 2

Cobalt Naphthanate (6%) part per 100 parts of resin by wt. .03

An epoxy/polyamide resin composition is as follows:

Parts by wt. Versamid 115 polyamide resinGeneral Mills Co. 50 BakeliteERL 2795 epoxy resin 50 AFD filler (Aluminum Flake Co.)

The following are examples of spraying type room-temperature epoxy resincompositions:

Solid tough typeEpoxy resin: softening point C.) mercury method Durranss70 Specific gravity 1.21 Weight per gallon (lb.) 10.1

Viscosity (40% in butyl Carbitol) Parts by wt. Bulking value (gaL/lb.).099 Color (40% in butyl Carbitol) 4 Esterification equivalent (grams ofresin esterified by l gram-mole of monobasic acid) Epoxide equivalent(grams of resin containing 1 gram equivalent of epoxide) 485 Epoxy value(epoxide equivalents per 1000 grams of resin) 2.05

A specific formulation for spraying:

Parts by wt. Epoxy resin 580 Toluol 195 MIBK Butyl Cellosolve 20Dissolve and add: Beetle 216-8 (60%) 30 1,000 Before use, reduce theabove with:

Parts by wt. Diethylene triamine (6% on solids) 36 Xylol l8 ButanOl 1872 Then add the following solvent-blend to obtain the desired viscosity:Toluol 500 MIBK 450 Cellosolve 50 1,000 To cure bake for 20 minutes at200 F. 4 minutes at 350 F. 10 minutes at 250 F. 2 minutes at 400 F. 7minutes at 300 F. 1 minute at 450 F.

Polyamide portion made as follows:

Parts by wt. Versamid 115 600 Toluol 360 Cellosolve 40 Final blendmixing: Percent parts by wt. Resin portion 65 to 68 Polyamide portion 32to 35 Make the final blend just prior to use. Thin to viscosity desiredwith the following solvent-blends.

An epoxy resin combined with polysulfide rubber resin is as follows:

Lbs. G a].

Resin Portion:

Epoxy Resin-Araldite 6010 260 26. 70 Araldite 6071 V 175 17. 33

BK 1 104 15. 51) Beetle 2168 r l 39. 25 4. 61 Polysulfide Portion:

Thiokol Ll 3 217 20. 50 DMP-3O 1 44 5. 36 MEK 67.10 10.00

23 Naugatuck, Conn.; Lupersol DDM, methylethyl ketone peroxide, aproduct of Wallace and Tiernan Co., Buffalo, New York; Bakelite ERL2795, an epoxy resin, a product of Union Carbide Co.; Beetle 2l68,Urea-formaldehyde solution of 60% solids used to decrease surfacetension and aid leveling properties, a product of Union Carbide Co., andothers; AFD Filler, an aluminum filler, a product of Aluminum Flake Co.,New York, N.Y.; Araldite 6071 epoxy resin, a product of Ciba Co.,Fairlawn, N.J.; Thiokol LP-3, polysulfide rubber resin, a product ofThiokol Chemical Corp., New York, NY.

A variety of fillers, pigments, and dyes can be incorporated into eitherone or both of the component parts. Titanium dioxide, zinc sulfide,silica, carbon black, and powdered aluminum may be used. However,aluminumtype fillers should be added only to the resin portion as theamine-catalyst (DMP30) in the polysulfide portion will react with theseafter prolonged contact. These mixtures will cure at room temperaturesor at elevated temperatures in from 3 days at 60 to 90 F. to 3 min. at350 F. with temperature being the direct factor of time in the cure.

The knowledge of the art of such resin compounding is constantlyexpanding and the examples given are for illustration and are notlimiting upon the examples given as the invention here disclosed appliessuch art to the combination of concrete or other porous structuralmaterial as available for the pipe, tanks or vessels made with resincompositions, elastomeric composition and synthetic or rubberymaterials.

One of the important elements is the shrinkage factor of each resin orcombination of resins or discrete selected components used in theformulations containing resins since the forces developed by theshrinkage or otherwise induced into the composite pipe structure orvessel structure are put to work to prestress the constructions. Anotherimportant element is the adhesive and bonding strengths developed by theresins and other discrete components. The penetrating and permeatingcharacteristics of resins and forces derived from manually, mechanicallyor capillary induced force systems are factors in the strucrtural designof constructions. The relationship to temperatures and changes thereofand particularly ambient temperatures will partly determine selection ofresins used for specific constructions.

The fibers selected are subject to stress analysis and each use dictatesselection based on cost, availability and strength characteristics.Fiber glass fibers at present are preferred as the highest strengtheconomical material (300,000 to 1,000,000 or p.s.i. ultimate strength intension) with respect to tension loading. Fiber glass fibers have otherdefinite advantages and characteristics inherent to its nature. Thisdoes not preclude any other fiber or strand adapted to any use in thisinvention being used where necessary.

Concrete and other porous structural materials are depended upon almostuniversally. There are many aggregate sources by which the engineer candesign and construct good concrete or porous structural materialqualities. Volcanic derived aggregates, man made calcined materials,selected rock and sand aggregates and any other commercially practicalconcrete materials used. Portland cements, natural cements, and resinbinders are used to make concrete and concrete-like materials in thefull measure of the art.

It is understood that it is intended to cover all changes andmodifications of the examples of the invention herein chosen for thepurpose of illustration which do not constitute departures from thespirit and scope of the invention.

Having disclosed numerous embodiments of my invention, I claim:

1. The method of making a reinforced composite concrete pipe havingsubstantial resistance to impact and dynamic loading, and beingsubstantially impervious to the entrance of adverse chemicals throughsaid concrete (1) provide a porous concrete pipe body having open poresand interstices connected therewith, said pores and interstices being atleast in the neighborhood of the surface of said concrete pipeconstruction;

(2) substantially penetrate and permeate said pores and interstices ofsaid porous concrete pipe body, and fill and cover said surface of saidconcrete pipe body with a tough, rubbery resin composition and provide asurplus of said resin composition on said surface thereover;

(3) lay and cross-lay a plurality of glass fiber strands on said surfaceof said concrete pipe body in said tough, rubbery resin composition;

(4) set and cure said resin composition to its cured state whereby saidreinforced concrete pipe is ready for use.

2. The method of making a reinforced concrete pipe as in claim 1, inwhich said tough, rubbery resin composition has shrinkage forces andcapture said shrinkage forces as internal stress in the body of theporou structure of said concrete pipe body, said internal stresscomprising prestressed preload in said composite concrete pipe inreinforcement thereof, said tough, rubbery resin composition beingselected from the group consisting of unsaturated polyester resins,epoxy resins having a curing agent there for, silicone resins,polyurethane resins, vinyl resins, unsaturated polyester-epoxy resins,unsaturated polyesteracrylic resins, epoxy-polyamine resins,epoxy-polyamide resins, epoxy-polysulfide resins, epoxy-coal tar resins,epoxy-vinyl chloride resins, epoxy-asphaltic resins, epoxyphenolicresins, epoxy-fluorinated resins, epoxy-urea formaldehyde resins,epoxy-furfural resins, epoxy-isocyanatepolyurethane resins,epoxy-polyethylene resins, epoxymelamine formaldehyde resins, andepoxy-silicone resins.

3. The method of making a reinforced composite concrete pipe as in claim1, in which in addition lay and cross-lay said glass fiber strands inhelically disposed con tinuous unidirectional winding and pretensionsaid strands prior to their being laid in said resin composition on saidsurface of said concrete pipe body.

4. The method of making a reinforced composite concrete pipe as in claim2, in which in addition place said concrete pipe body under compressiveprestressed preload prior to penetrating and permeating the pores andinterstices of said concrete pipe body with said tough, rubbery resincomposition and capture said induced compressive prestressed preload insaid concrete pipe body when said resin composition sets and cures toits set state.

5. The method of making a reinforced composite con crete pipe as inclaim 4, in which in addition provide said concrete pipe body with aplurality of grooves spaced around its circumference and in said groovesembed longitudinal fibrous tensile reinforcements.

6. The method of making a reinforced composite concrete pipe as in claim1, in which said tough, rubbery resin composition has a filler therefor.

7. The method of making a reinforced composite concrete pipe as in claim1, in which said tough, rubbery resin composition comprises anunsaturated polyester resin composition having a substantial shrinkageupon cure applied in between, on and about the individual fibers of saidglass fiber strands.

8. The method of making a reinforced composite concrete pipe as in claim7, in which in addition an epoxy resin composition having a curing agenttherefor is used in combination with said unsaturated polyester resincomposition.

9. The method of making a reinforced composite concrete pipe as in claim1, in which in addition, provide an inside pipe liner therefor,

provide a polished mandrel for insertion into the inside of the saidconcrete pipe body;

next, apply to said mandrel a layer of mold release followed by a layerof polymerizable plastic tough, rubbery resin composition and while saidresin composition is in its polymerizable condition, embed and wind onsaid mandrel in said resin composition a plurality of helically disposedlayers of long strands of high strength tensile material in lay andcross-lay pattern to provide a selected cross-sectional amount of saidtensile material;

next, apply additional resin composition to a surplus over that neededto impregnate said long strands of high tensile material, said resincomposition penetrating and permeating the porous structure of said concrete pipe body when said layers of strands are combined with saidconcrete pipe body;

next, heat said concrete pipe body on its inside surface and slightlyexpand said concrete pipe body and then insert said mandrel havingthereon said impregnated strands and surplus of said resin compositioninto said inside of said concrete pipe body and thereby form said insidepipe liner;

next, cure said resin composition and when said pipe liner is cured,remove said mandrel making said composite concrete pipe ready for use.

10. The method of making a reinforced composite concrete pipe as inclaim 2, in which in addition place said porous concrete pipe body undercompressive stress;

next, with said porous concrete body under compressive stress spray-spina polymerizable tough, rubbery resin composition-fiber reinforcedlaminated layer on the inside surface of said porous concrete pipe bodyuntil a selected amount of said plastic resin fiber laminated layer isprovided on said inner surface of said concrete pipe body;

next, while spray-spinning said polymerizable plastic resin-fiberlaminated layer, provide curing means for said polymerizable plasticresin composition and cure it to a set state thereby making saidcomposite concrete pipe ready for use.

11. The method of making a reinforced composite concrete pipe as inclaim 10, in which said concrete pipe body is rotated at a selectedspeed whereby said fiber of said construction is deposited by gravity ina position above an initial application of said resin composition and inbetween the surface of the concrete pipe body and the exterior face ofsaid plastic resin composition, said fiber having a specific gravitygreater than the initial application of plastic resin composition, saidinitial application of plastic resin composition being cured by means,for example, heat, so that it retains said fiber in its body and abovesaid concrete surface of said concrete pipe body.

12. The method of making a reinforced composite concrete pipe as inclaim 11, in which said initial application of resin compositioncontains a filler provided to at least increase the specific gravity ofsaid composition equal to said fiber.

13. The method of making a prestressed integrally laminated hollowcylindrical construction comprising the steps of:

(1) provide at least one preformed cylindrical hollow body of porousstructural material;

(2) apply to the inside surface of said body a mass of polymerizableplastic resin composition and a filler therefor having a selected amountof shrinkage when set, said composition having a predetermined selectedviscosity;

(3) place said cylindrical body on a spinning apparatus and spin saidbody at a selected speed and provide centrifugal forces of selectedmagnitudes, spinning said body with said mass of polymerizable plasticresin composition and filler therefor to evenly spread saidpolymerizable plastic resin composition and filler therefor to a compactsurface layer construction on said inside surface of said body to forceintegrating 26 portions of said polymerizable plastic resin compositioninto the surface of said body and penetrate said surface and permeatethe porous structural material adjacent said surface, said integratingportions forming anchoring resin bodies in said porous structuralmaterial and said pores thereof;

(4) cure said polymerizable plastic resin composition to a set plasticresin composition whereby said shrinkage forces of said polymerizableplastic resin composition provide prestressed preload to said internallybonded and laminated hollow cylindrical construction;

(5) on completion of cure of said polymerizable plastic resincomposition remove said prestressed integrally laminated hollowcylindrical construction from spinning apparatus ready-for-use.

14. The method of making a prestressed integrally laminated hollowcylindrical construction as in claim 13, in which the magnitude of thecentrifugal forces applied by the said spinning step are varied duringthe cycle of spinning to dispose a portion of said polymerizable resincomposition into and on said porous structural material of saidcylindrical construction, and dispose said filler in said resincomposition on said surface of said porous structural material, anddispose the remainder of said polymerizable resin composition to form asmooth surface thereover whereby the said filler forms a high strengthtensile reinforcement securely anchored into and on and with said porousstructural material of said hollow cylindrical construction.

15. The method of making a composite concrete pipe body adapted tosupport substantial interior pressures and external loading comprisingthe steps of:

(1) provide a substantially dried, precast and cured concrete pipe bodyhaving open pores and interstices connected therewith, said pores andinterstices being at least in the neighborhood of the surface of saidconcrete pipe construction;

(2) apply to the exterior surface of said composite concrete pipe bodyan initial layer of polymerizable polymeric resin composition forpenetrating and permeating said resin composition particularly into saidpores and interstices of said concrete pipe body to fill the same, saidpolymerizable polymeric resin composition having selected shrinkageforces which provide internal stress in compression and provide therebyprestressed preload induced into said concrete material of said concretepipe body, said polymerizable polymeric resin composition having asurplus of resin composition on the said exterior surface of saidconcrete pipe body;

(3) apply a plurality of unidirectional strands of high tensile strengthfibers spaced substantially equidistant from each other on said surfaceof said concrete pipe body under tension to provide compressive forcesagainst said surplus of said polymerizable polymeric resin composition,said compressive forces causing a portion of said polymerizablepolymeric resin composition to penetrate and permeate into the saidconcrete pipe body and fill said pores and interstices connectedtherewith;

(4) apply additional polymerizable polymeric resin composition and embedsaid strands of said fibers in said polymerizable polymeric resincomposition so that all of said fibers are substantially covered;

(5) initiate and activate said polymerizable reaction by the resincomposition by heat and cure the said resin composition in the pores andinterstices of said concrete pipe body and on its surface and about itshigh strength unidirectional fiber strands in said resin compositionwhereby said resin composition during its polymerization and cureprovides said shrinkage forces, which forces are captured in place assaid prestressed preload by said resin composition in its cured and setstate and thereby bonds and integrates the said concrete pipe body, thesaid unidirectional high strength fiber strands and the said resincomposition into said composite concrete pipe body.

16. The method of making a prestressed reinforced composite concretepipe comprising the steps of:

(1) provide a substantially dried precast cured concrete pipe bodyhaving open pores and interstices connected therewith extending from theinside to the outside of said concrete pipe body, and said insidesurface of said concrete pipe body being circular and planar, saidexterior surface of said concrete pipe body having in the pipe wall aseries of grooves extending longitudinally of said concrete pipe body;

(2) place said dried precast cured porous concrete pipe body into aprestressing harness and induce and hold compressive prestressed preloadinto said concrete pipe body by mechanical'means;

(3) apply a layer of flowable impregnating polymerizable polymeric resincomposition to said inside surface of said pipe body and evenlydistribute and smooth said polymeric resin composition and penetrate andpermeate it into the open pores and interstices connected therewith ofsaid wall of said concrete pipe body;

(4) next place a glass fiber material on said polym erizable polymericresin composition on said inside surface of said pipe body andsubstantially completely embed said glass fiber material in saidpolymerizable polymeric resin composition and with a surplus thereover,said surplus having a mineral filler therefor;

(5) partially gel said polymerizable polymeric resin composition againstflow;

(6) place sized longitudinal cables comprised of pluralities ofunidirectional glass fiber roving strands into said longitudinal grooveson the external face of said concrete pipe body and secure saidlongitudinal cables of said glass fiber roving strands under tension tosaid external face of said concrete pipe body in said grooves byapplying adhesive polymerizable polymeric resin composition, and cover,penetrate and permeate said adhesive polymerizable polymeric resincomposition into said pores and interstices connected therewith of saidexternal face of said concrete pipe body and into engagement into thepipe body with said first applied polymerizable polymeric resincomposition previously penetrated and permeated from the inside surfaceof said wall of said concrete pipe body and gel same against flow;

(7) apply polymerizable polymeric resin composition covered continuousunidirectional fiber glass fiber roving strands under tension inhelically disposed winding and cover said grooves and said embeddedlongitudinal cables of said glass fiber roving strands in said groovesand cover substantially completely said external surface of saidconcrete pipe body;

(8) apply additional polymerizable polymeric resin composition having amineral filler therefor to the exposed surface remaining on the externalface of said concrete pipe body;

(9) polymerize and cure said resin compositions to a final state ofcure;

(10) when said resin compositions are cured, release said prestressingharness and remove said finished prestressed reinforced concrete pipeready for use.

17. The method of making a prestressed reinforced concrete pipeconstruction having substantial impact resistance to dynamic loading andbeing substantially impervious with high shielding properties providingprotection against dynamic loading and resistance to the entrance ofadverse chemicals into said pipe construction comprising the steps of:

( 1) provide at least one precast porous reinforced concrete pipe bodyand place said concrete pipe body in a rotatable prestressing harnessand mechanically induce and hold a predetermined selected prestressedpreload into said concrete pipe body;

(2) heat and dry said concrete pipe body to substantially providemaximum commercially obtained aridity in said concrete pipe body toprovide open pores and interstices connected therewith available forimpregnation with a flowable tough, rubbery polymerizable polymericresin composition;

(3) while said concrete pipe body is at a temperature above ambienttemperature but lower than curing temperature of said polymeric resincomposition, rotate said pipe body in said rotatable prestressingharness and substantially fill said open pores and interstices connectedtherewith with polymerizable polymeric resin composition onto and intosaid inside surface of said concrete pipe body and provide a surplus ofsaid polymerizable polymeric resin, composition thereover;

(4) next partially gel said polymerizable polymeric resin compositionagainst flow;

(5) continue to rotate said concrete pipe body at a rate of rotationholding said polymerizable polymeric resin composition in place asplaced and while said rotation is in progress, apply a layer of glassfibers to said inside surface of said concrete pipe body and utilize thecentrifugal force of rotation to firmly embed said glass fibers in saidpolymerizable polymeric resin composition and spray spin additionalresin composition having a filter therefor to substantially completelycover said glass fibers as embedded making a smooth surface thereover;

(6) next gel said resin composition against flow;

( 7) turning now to the outside surface of said concrete pipe, body,next apply a layer of fiowable, tough rubbery structural reinforcingpolymerizable p0ly meric resin composition having a filler thereforhaving shielding properties on said outside surface of said concretepipe body and penetrate and permeate said flowable resin compositioninto said pores and interstices connected therewith substantially indepth throughout said porous structure of said concrete pipe body;

( 8) while said flowable resin composition advances to a gel state ascuring proceeds, apply a plurality of glass fiber roving strands inpredetermined selected directional placement under tension andsubstantially completely cover and embed said glass fiber roving strandsWhile in said state of tension and form a layer of structuralreinforcement and impervious characteristic with said resin compositionhaving fingers" and projections thereof extending into deep engagementwith the porous structure of said concrete pipe body and at leastpartially engaging said polymeric resin composition first applied ontoand into said inside surface of said concrete pipe body;

(9) while said polymeric resin composition is still in its uncuredstate, apply an additional layer of polymerizable polymeric resincomposition having a lead powder filler and substantially cover saidoutside surface of said previously applied glass fiber roving strandsand their embedded polymeric resin composition and build up a designatedthickness layer of lead filler in said polymerizable polymeric resincomposition;

(lO) while applying said lead powder filler in said polymerizablepolymeric resin composition, apply heat to said inside and outsidesurfaces of said concrete pipe body as covered and gel and cure saidresin compositions against flow until said resin compositions reachtheir cured state and integrated structure;

( l i) allow said now completed prestressed reinforced concrete pipeconstruction to cool to ambient temperature and at this temperaturerelease said prestressing harness from its compressive loading andholding of said concrete pipe body and remove said prestressedreinforced concrete pipe body construction ready-for-use.

18. The method of making a prestressed reinforced composite concretepipe as in claim 17 in which said polymerizable polymeric resincomposition is selected from the group consisting of unsaturatedpolyester resins, epoxy resins having a curing agent therefor andpolyurethane resins.

19. The method of making a prestressed reinforced composite concretepipe as in claim 17 in which said polymerizable polymeric resincomposition includes as a component therefor a thermoplastic resincomposition.

20. The method of making a prestressed reinforced composite concretepipe as in claim 17 in which said polymerizable polymeric resincomposition is thermosetting and as a component thereof includes anelastomeric resin composition providing elasticity to the structure.

21. The method of making a prestressed reinforced composite concretepipe as in claim 17 in which said glass fiber includes as a component ofsaid reinforcement a reinforcement selected from the group consisting ofaluminum silicate fibers, fuzed quartz fibers, spun ceramic fibers,asbestos fibers, and metal wires.

22. The method of making a prestressed reinforced composite concretepipe as in claim 17 in which said polymerizable polymeric resincomposition includes as a filler thereof a filler selected from thegroup consisting of silica minerals, aluminum silicate minerals,short-fibered asbestos, ignited aluminum trioxide, titanium dioxide,calcium carbonate, sand and lead powder.

23. The method of making a prestressed reinforced composite concretepipe as in claim 17 in which said glass fiber unidirectional rovingstrands are used in combination with organic fibers selected from thegroup consisting of sisal fibers, hemp fibers, and cotton fibers.

24. The method of making a prestressed reinforced composite concretepipe as in claim 17 in which said glass fiber unidirectional rovingstrands are used in combination with synthetic fibers selected from thegroup consisting of nylon fibers, rayon fibers, polyethyleneterephthalate fibers, acrylic fibers, and metal wires.

25. The method of making a prestressed reinforced composite concretepipe as in claim 17 in which said glass fiber unidirectional rovingstrands are used in combination with fiber glass fiber multidirectionalglass fiber mat, woven glass fiber roving, loosely applied fibers ofglass and glass fiber cloth as selected for specific constructions.

26. The method of making a reinforced composite concrete pipe, beingsubstantially impervious to the entrance of adverse chemicals throughsaid concrete pipe:

(I provide a porous concrete pipe body having open pores and intersticesconnected therewith, said pores and interstices being at least in. theneighborhood of the inside surface of said concrete pipe construction;

(2) provide a mandrel for insertion into the inside of the said concretepipe body;

(3) apply to said mandrel a layer of polymerizable plastic resincomposition and while said resin composition is in its polymerizablecondition, embed and wind on said mandrel in said resin composition aplurality of layers of fibrous material;

(4 apply additional resin composition to a surplus over that needed toimpregnate said fibrous material, said resin composition penetrating andpermeating the inside surface of said concrete pipe body when saidlayers of fibrous material are combined with said concrete pipe body;

(5) insert said mandrel having thereon said impregnated fibrous materialand surplus of said resin composition into said inside of said concretepipe body and thereby form a pipe liner; and

(6) cure said resin composition and when said pipe liner is cured,remove said mandrel making said composite concrete pipe ready for use.

27. The method of making a prestressed reinforced composite concretepipe as in claim 26, in which said polymerizable polymeric resincomposition is selected from 30 the group consisting of unsaturatedpolyester resins, epoxy resins having a curing agent therefor andpolyurethane resins.

28. The method of making a prestressed reinforced composite concretepipe as in claim 26, in which said polymerizable polymeric resincomposition has a filler therefor.

29. The method of making a prestressed reinforced concrete pipeconstruction, having substantial resistance to the entrance of adversechemicals into said pipe construction comprising the steps of:

(I provide at least one precast porous reinforced concrete pipe body andplace said concrete pipe body in a rotatable prestressing harness andmechanically induce and hold a predetermined selected prestressedpreload into said concrete pipe body;

(2) apply on the inside surface of said pipe a flowable polymerizablepolymeric resin composition;

(3) rotate said pipe body in said rotatable prestressing harness andsubstantially fill said open pores and interstices on the inside surfaceof said pipe with said polymerizable polymeric resin composition andprovide a surplus of said polymerizable polymeric resin compositionthereover;

(4) continue to rotate said concrete pipe body and while rotating saidpipe apply a layer of glass fibers to said inside surface of saidconcrete pipe body and utilize the centrifugal force of rotation tofirmly embed said glass fibers in said polymerizable polymeric resincomposition;

(5) apply additional resin composition to substantially completely coversaid glass fibers as embedded making a smooth surface thereo er; and

(6) next gel said resin composition against flow.

30. The method of making a prestressed reinforced composite concretepipe as in claim 29, in which said polymerizable polymeric resincomposition is selected from the group consisting of unsaturatedpolyester resins, epoxy resins having a curing agent therefor andpolyurethane resins.

3]. The method of making a prestressed reinforced composite concretepipe as in claim 29, in which said polymerizable polymeric resincomposition has a filler therefor.

32. The method of making a prestressed reinforced concrete pipeconstruction having substantial impact resistance to dynamic loading,comprising the steps of" (1) provide a porous concrete pipe body havingopen pores and interstices on the outside surface thereof,

(2) apply a layer of flowable, polymerizable polymeric resin compositiononto and into said outer surface of said pipe body;

(3) apply glass fiber materials under tension onto said outer surfaceand substantially completely cover and embed said glass fiber materialswhile in said state of tension and form a layer of structuralreinforcement and impervious characteristic with said resin com positionhaving fingers and projections thereof extending into said porousstructure of said concrete pipe body, and

(4) cure said resin compositions against flow until said resincompositions reach their cured state and integrated structure.

33. The method of making a prestressed reinforced composite concretepipe as in claim: 32, in which said polymerizable polymeric resincomposition is selected from the group consisting of unsaturatedpolyester resins, epoxy resins having a curing agent therefor andpolyurethane resins.

34. The method of making a prestressed reinforced composite concretepipe as in claim 32, in which said polymerizable polymeric resincomposition has a filler therefor.

(References on following page) patent.

References Cited The following references, cited by the Examiner, are ofrecord in the patented file of this patent or the original UNITED STATESPATENTS Illernann 264-270X Vianini 138-176 Carson 264-270-X Miller et a1138-176 Cornelius et a1. 264-270X Ellis 260-174 Scripture 117123Jackson.

Vessels 156-172X Upson 138-176 Bickel et a1 264-265 Goldfein 264-228XSergovic 11794X Noland et a1. 156-161X LELAND A. SEBASTIAN, PrimaryExaminer US. Cl. X.R.

